1. Field of the Invention
The present invention relates to an image formation apparatus and an image formation method for forming an image on continuous paper, and to an image formation apparatus and an image formation method that can correct the deviation of paper in a main scanning direction.
2. Description of the Related Art
For example, an image formation apparatus that performs printing with the use of continuous paper such as roll paper has been suggested. In an image formation unit of such an image formation apparatus using the roll paper, a latent image corresponding to a document is formed on a photosensitive body, toner is applied to this latent image for development, and this developed toner image is transferred to paper. After that, the toner image on the paper is fixed by a fixing unit and the paper is discharged. The roll paper is usually housed in a paper feed unit and when an image is formed, the paper is fed from the paper feed unit by a paper conveyance unit and conveyed to the image formation unit.
In this case, the paper is deviated in a main scanning direction due to the deviation of the timing of feeding the paper or the vibration or the aging of components in the conveyance of the fed paper, resulting in that the position at which the image is to be formed is displaced.
For solving the above problem, for example, JP 2008-126530 A discloses an image formation apparatus in which an end of the paper is photographed when the roll paper starts to be fed, the positional data of the end of the paper is calculated, the drawing release start position of the print data is decided on the paper based on the calculated positional data, and the position of the paper is adjusted by the inkjet head or the encoder. Moreover, JP 2012-189672 A discloses an image formation apparatus in which, if the deviation of the paper has been detected, the position where the writing of the image by the exposure unit is started is corrected and additionally, the resist rollers are shaken to move the paper conveyance position (position where the paper is conveyed in the paper width direction). Moreover, JP H8-119503 A discloses an image recording apparatus in which a difference is provided in the pressing force operating at opposite ends of a correcting roller provided across the entire width of the paper when the continuous paper is conveyed, whereby a difference is caused in the conveying force operating in the paper width direction to correct the displacement of the paper.
In the image formation apparatus according to JP 2008-126530 A, however, the deviation of the roll paper that has occurred after the drawing of the data is released is not considered and therefore if the paper position has changed in the conveyance, the image drawing position may be displaced. Moreover, in the image formation apparatus according to JP 2012-189672 A, the target is a cut sheet; therefore, the paper position cannot be changed unless the crimp throughout the conveyance path is released, and moreover, in the case of using the roll paper, the conveyance becomes difficult if the crimp is released in the conveyance of the paper. Thus, JP 2012-189672 A cannot be applied to the roll paper. In the image recording apparatus according to JP H8-119503 A, a special mechanism is necessary to correct the displacement in the paper conveyance, which costs high.